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CATEGORY:
Astrophysics Seminar
TITLE:
AGN/XRB warm absorbers: a key to their broader phenomenology
Speaker:
Demos Kazanas
Affiliation:
NASA
WHEN:
Wednesday
24/05/2017, 14:30 - 15:30
WHERE:
Lidow, 620
Organizer:
-
Site:
-
Remarks:
-

Abstract

An increasing number of observations have indicated the presence of blue shifted
absorption features in the X-ray spectra of both AGN and accreting galactic X-ray
binaries that span a large range in ionization parameter and velocity. These have
been attributed and successfully modeled by accretion disk winds. Moreover, the
dependence of their column density on their ionization parameter has allowed to
determine the wind density profile along the observer's LoS and hence the
corresponding wind mass flux. This was found to be an increasing function of the
distance from the X-ray source, with the corresponding mass flux much larger than
that needed to produce, by accretion, the observed X-ray luminosity. This signifies
that the disk accretion rate decreases with radius, much of is mass flux diverted
into the wind. This decreasing accretion rate in the disk, then, makes it possible
for its inner regions to revert to a hot, X-ray emitting ADAF state, while its
cooler, BBB component to be emitted at larger radii, despite the fact that it is more
luminous, in agreement with microlensing observations. It will be argued that an
increase in the overall supply of matter to the black hole can under these
assumptions reproduce much of the global spectral AGN/XRB phenomenology, in
particular the AGN $\alpha_{OX}$ dependence on luminosity and their warm absorber
properties.

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